A liquid crystal alignment treating agent containing a polyamic acid which is represented by the following formula (I) and exhibits a reduced viscosity of from 0.05 to 5.0 dl/g (in N-methyl-2-pyrrolidone at 30.degree. C. at a concentration of 0.5 g/dl) or a polyimide obtained by cyclodehydration thereof: ##STR00001## wherein R.sup.1 represents a tetravalent organic group, at least 20 mol % of which has a fused alicyclic structure composed of two to five rings, and all of the carbonyl groups are directly bonded to the alicyclic structure and that any two carbonyl groups are not bonded to adjacent carbon atoms of the alicyclic structure; R.sup.2 is a bivalent organic group, from 20 to 100 mol % of which has in the side-chain structure at least one structural unit selected from the group consisting of C.sub.5-20 long-chain alkyl, C.sub.5-20 fluoroalkyl, alicyclic structures and aromatic ring structures; and L is a positive integer.